Fall 2010 IAB
September 15 to 17

Mark Hersam, Northwestern University

Preparation and Characterization of Monodisperse Carbon Nanotube Materials and Devices

Large-scale production of high purity carbon nanotubes has the potential to enable or improve many applications [1]. Recently, we have developed a scalable and flexible technique for sorting single-walled carbon nanotubes (SWNTs) by their physical and electronic structure using density gradient ultracentrifugation (DGU) [2]. Diameter-sorted metallic SWNTs yield semi-transparent conductive films with tunable optical absorption [3]. On the other hand, semiconducting SWNTs enable thin film transistors with high switching ratios and drive currents [4]. Most recently, chiral surfactants have been utilized for DGU-based sorting of SWNT enantiomers [5]. In all cases, analytical ultracentrifugation measurements allow the SWNT surfactant loading to be quantified and optimized for improved DGU sorting [6]. This talk will also delineate DGU sorting of double-walled carbon nanotubes (DWNTs). Since DWNTs possess a buoyant density that is intermediate between SWNTs and multi-walled carbon nanotubes, a two-step DGU process has been developed for high purity DWNTs [7]. DGU-sorted DWNTs enable characterization of the fundamental properties of DWNTs and yield high performance transparent conductive films.

[1] M. C. Hersam, Nature Nanotechnology, 3, 387 (2008).
[2] M. S. Arnold, et al., Nature Nanotechnology, 1, 60 (2006).
[3] A. A. Green and M. C. Hersam, Nano Letters, 8, 1417 (2008).
[4] M. Engel, et al., ACS Nano, 2, 2445 (2008).
[5] A. A. Green, et al., Nano Research, 2, 69 (2009).
[6] M. S. Arnold, et al., ACS Nano, 2, 2291 (2008).
[7] A. A. Green and M. C. Hersam, Nature Nanotechnology, 4, 64 (2009).